This invention relates to a paving machine, more particularly a machine for spreading and levelling concrete, as well as to a method for forming a concrete path.
As known, such paving machines are used for forming a variety of concrete pavings, in the first place for forming concrete roadways, but, furthermore, also for forming large concrete floors and such.
It is known that such paving machines mostly consist of a movable frame at which one or more processing devices for processing the concrete are fixed or can be fixed. Mostly, use is made of several processing devices providing for different processings, such as spreading the concrete, which has been poured in front of the device, in width, vibrating the concrete, drawing the concrete into a shape, providing dowels in the concrete, smoothing the concrete by means of a smoothing beam and finishing by means of a smoothing board moving to and fro.
It is also known that such paving machines, including the processing devices, can be made extensible in order to be able to adjust the working width. An example thereof is known from the international patent application WO 95/28525. In such case, the frame as well as the processing devices are telescopically extensible, whereby the processing devices then consist of several parts which telescope either in each other or along each other or at a distance behind each other.
Such paving machines, the processing devices of which consist of several parts which together must span the working width, and especially paving machines with parts which, as aforementioned, are extensible in respect to each other, show the disadvantage that the mutual position of the parts of one and the same processing device may change during paving, as a result of sagging under the weight of the paving machine and/or as a result of the pushing in upward direction, when, centrally below the paving machine, a surplus of concrete is poured. This has as a consequence that the surface of the formed concrete path deviates from the desired shape. It has already been proposed to remedy this by using manually turnable screw jacks with which the mutual position of the aforementioned parts can be adjusted. This solution, however, has the disadvantage that it is less efficient, as in practice an adjustment exclusively will be carried out when major, visually discernible deviations occur.
Further, it is also known that paving machines can be equipped with oscillating finishing beams for assisting in smoothing the concrete of the path surface. An example thereof is described in U.S. Pat. No. 5,941,659, in which two finishing beams, situated at a distance from each other according to the direction of movement, are applied, i.e. one finishing beam performing a substantially vertical oscillation, and a finishing beam performing a substantially horizontal oscillation. The vertical oscillation has as a purpose, so to speak, to tamper the gravel in the concrete into the surface, whereas the horizontal oscillation additionally smoothes the concrete at the surface. In that hereby use is made of two oscillating finishing beams cooperating with one and the same path surface, such embodiment, however, shows the disadvantage that the average positions which are taken by these finishing beams in respect to the formed path surface, have to be precisely coordinated in mutual respect, and that, with certain deviations, malfunctions in the faultless working may occur. Another disadvantage consists in that two separately driven systems, one behind the other, are necessary, as a result of which the total length of the paving machine, seen according to the paving direction, is influenced in a disadvantageous manner.
The present invention aims at a paving machine, whereby various improvements are intended which contribute to a better quality of the obtained concrete path and/or which allow for performing a more efficient control of the quality of the realized concrete path.
According to a first aspect of the invention, a paving machine is aimed at, with one or more processing devices consisting of two or more parts which together span the working width, whereby a solution is offered for efficiently excluding or minimizing deviations in the surface of the concrete path which arise as a consequence of undesired alterations in the mutual position of such parts. More particularly, according to this first aspect, it is aimed at excluding or at least minimizing undesired deviations as a result of the sagging of the paving machine and/or the pushing-up of parts thereof.
According to this first aspect, the invention thus relates to a paving machine, comprising a movable frame with at least one processing device for processing the concrete which extends according to the working width and which consists of at least two parts,or otherwise called screed elements, which possibly are movable in respect to each other, in order to adjust the span of the processing device, with as a characteristic that the paving machine comprises means, or otherwise called a control device, on one hand, directly or indirectly, control the mutual position of said parts, such in respect to the surface to be formed, as well as, on the other hand, allow for adjusting the mutual position in function of said control.
By providing the paving machine with means which, on one hand, allow for such control and, on the other hand, allow for an adjustment, a very precise follow-up of the mutual position of said parts is possible, and it is possible to rapidly take measures in order to remedy any undesired alteration in the position by means of a corresponding adjustment.
Preferably, said means consist of detection means or otherwise called a detection device, performing observations in respect to said mutual position, as well as controllable adjustment means, or otherwise called an adjustable device, for commanding said parts in such a manner that a desired adjustment is realized. More particularly, it is preferred that the controllable adjustment means are coupled to the detection means, such that an adjustment is performed in function of a desired adjustment of the mutual position. Thereby, an automatic feedback is provided for, whereby the operator of the paving machine himself no longer has to perform any adjustments.
Although the invention allows to counteract a variety of deviations between the positions of the respective parts of a processing device, it is clear that said means, in the first place, are intended to control the sagging, pushing-up, respectively, of the processing device.
In a practical form of embodiment, the frame of the paving machine, as usual, comprises two side parts carried by movable support elements, and according to the present invention, said means are configured such that they provide for a control in respect to a reference line, reference plane, respectively, which connects the two side parts. In practice, paving machines in fact are kept at a well-defined height at these side parts, for example, by means of sensors which command the height of the side parts in function of pre-set level lines. In the proximity of the side parts, the obtained concrete path thus always is at the right height, and lines or planes connecting the two side parts therefore ideally may serve as a reference line or plane for performing said control.
In the case that use is made of such reference line or such reference plane, said parts, at their outwardly directed extremities, are connected to the side parts preferably at a well-defined height, whereas with their inwardly directed extremities, they can be adjusted in height by means of said controllable adjustment means. When the paving machine is realized in a classical manner, with a central basic frame and with side parts provided on frame parts which are extensible in respect to the basic frame, it is preferred that the controllable adjustment means are situated between the basic frame and said two parts of the processing device. As a result thereof, said parts can be easily drawn upward, pushed downward, respectively, in the middle of the span.
According to an important preferred form of embodiment, said means comprise detection means which are formed by, on one hand, at least one cable stretched over the width of the paving machine and, on the other hand, one or more sensors cooperating with said cable and said parts of the processing device, which deliver signals in function of the difference in height between said cable and said parts. By a cable, hereby any form of stretchable flexible element has to be understood, thus, also a rope, ribbon or such. Such cable has the advantage that it forms a stable reference line which can hardly be disturbed, on the basis of which line said detection can be performed.
In the case that the paving machine comprises one or more processing devices with two or more parts which are movable in respect to each other, in order to adjust the span of the processing device, processing devices, respectively, said means preferably will comprise separately controllable adjustment means per processing device and/or per part of such processing device. In this manner, the position of each processing device, and still more particularly each part thereof, can be adjusted separately, as a result of which any form of deviation can be excluded.
However, this does not exclude that according to a variant, a common detection, for example, in a central point, can be provided for, and possibly also an adjustment by means of adjustment means which are common for several processing devices and/or parts thereof.
In the case that several separately controllable adjustment means for different processing devices or parts thereof are used, the paving machine preferably comprises several cable lengths stretched over the width of the paving machine, substantially at the height of the respective parts to be controlled of the processing device, processing devices, respectively, which cooperate with respective sensors. In this manner, at different locations an efficient control can be provided.
Hereby, it is particularly useful that the respective cable lengths then form part of a single continuous cable which is stretched several times over the width of the paving machine, with the advantage that only one set of means for tensioning the cable is necessary, which means, for example, consist of at least one winding system for winding the cable at least at one end, and/or of at least one elastic tensioning means, or otherwise called an elastic tensioning device, such as a tension spring.
The aforementioned device proves its usefulness especially in combination with the form elements and smoothing beams usually applied with paving machines. These, in fact, are heavyweight items, the respective parts of which easily become displaced in respect to each other, especially if they are telescopic.
Said controllable adjustment means may be of different kind, however, for practical reasons, it is preferred that pressure cylinders are applied to this end. It is clear that said means can be provided at new paving machines as well as at already existing paving machines, or that new paving machines can be equipped with elements which allow the attachment of such means. Of course, the invention thus relates to all these cases. Taking this into account, the invention thus also relates to a paving machine comprising a movable frame with at least one processing device for processing the concrete, which latter device extends according to the working width and which consists of at least two parts which are movable in mutual respect in order to adjust the span of the processing device, with the characteristic that the paving machine comprises controllable adjustment means with which the mutual position of said parts, such in respect to the surface to be formed, can be adjusted.
According to a second aspect of the invention, which either may or may not be combined with the first aspect, an improved embodiment of a paving machine is intended which is provided with one and more oscillating finishing beams, whereby said disadvantages of the known embodiments are excluded or at least are minimized.
To this aim, the invention, according to this second aspect, relates to a paving machine for forming a concrete path, whereby this paving machine comprises at least one oscillating finishing beam, with the characteristic that it comprises drive means which allow the finishing beam to perform an upward and a sideward oscillation at the same time. It is clear that thereby at least several of said disadvantages of using two separate finishing beams, oscillating upward and sideward, respectively, are excluded.
It also became clear that by the combination of an upward oscillation and sideward oscillation at one and the same finishing beam, anyhow a better smoothing effect is obtained.
Preferably, the drive means for the oscillating finishing beam consist of at least two excenter mechanisms providing for the respective oscillations.
In the most preferred form of embodiment, the paving machine, according to its direction of movement during paving, will comprise exclusively one oscillating finishing beam, with the exception of possible overlapping portions when several finishing beams, whether telescopically adjustable or not, are active over the working width.
Preferably, the finishing beam is mounted at a smoothing beam, more particularly attached in front of such smoothing beam.
According to a particular form of embodiment, the finishing beam forms part of a paving machine which is adjustable, more particularly extensible, in the direction of the working width, and does this beam consist of several mutually displaceable parts, whether situated at a distance from each other or not, and us each part equipped with its own driving means for delivering the upward and sideward oscillations.
According to a third aspect of the invention, a paving machine is aimed at whereby at all times an efficient control of the concrete of the formed concrete path and/or of the shape of the concrete path can be performed. Up to the present, basically a control only can be performed by afterwards measuring the realized concrete path and/or taking samples by means of drilling. Such samples can only be taken after a sufficient hardening of the concrete in order to perform measurements thereon, as a result of which one mostly has to wait approximately two months before such samples can be taken and tested. According to the third aspect of the invention, an efficient control can be realized in a completely different manner.
Thus, according to the aforementioned third aspect, the invention relates to a paving machine for forming a concrete path, with as a characteristic that it is provided with registration means which at least register data relating to the formed concrete path. By means of these registration means, thus, controllable parameters are obtained, from which the quality and other characteristics of the formed concrete path can be derived.
Preferably, it comprises registration means registering at least one or more of the following parameters:
the width adjustment of the paving machine, more particularly of the working width;
the forward speed of the paving machine or of a value representative therefor;
the covered distance;
the oscillation speed of vibrating means, such as vibrating needles, for vibrating the concrete;
the thickness of the concrete path, possibly derived from other parameters;
when a concrete path is poured having a roof-shaped profile, the inclination of the roof-shaped profile;
the consumed quantity of concrete.
In the most preferred form of embodiment, at least two parameters are registered, on one hand, a parameter directly or indirectly related to the speed of the paving machine during paving, and, on the other hand, a parameter directly or indirectly related to the drive of the vibrating means for vibrating the concrete. The connection between these two parameters in fact forms a strong indication for the quality of the concrete. Possibly, this connection also may be formulated in a value, which value then has to be within well-defined limits. It is well-known that, in order to still enable a further paving of the path when the concrete is too wet or too dry, one may locally vibrate the concrete to a major or minor degree, as a result of which it is actually possible to continue working, but this mostly results in a diminishing quality of the concrete. By now following, by means of the registration means, the ratio between the parameters of vibrating and the parameters of the speed of forward movement, it will be automatically known whether the concrete will fulfill the quality requirements or not.
By means of said registration means, it is also possible to know where the most critical concrete parts are situated, where then possibly additional controls, by means of taking concrete samples, can be performed.
By means of the registration means, it can also be followed up whether a sufficient quantity of concrete per length unit has been applied and/or whether the realized concrete path thus also has a sufficient thickness.
The registered data can be registered in different manners, preferably in function of time and/or in function of the covered distance. For instance, the registration may take place by representing the data on a strip of paper, whether in the shape of curves or not, and/or by electronically storing these data, after which they can be visualized on a monitor and/or can be printed.
According to another variant, these data automatically will be transmitted to a central unit or a control authority, possibly still during the operation of the concrete paving machine, for example, by means of a wireless connection, for example, a telephone connection, more particularly by means of a cellular phone system or such.
According to a fourth aspect, the invention also relates to a paving machine for forming a concrete path, with as a characteristic that it is provided with a computer system with a monitor upon which one or more of the following data can be visualized:
the width adjustment of the paving machine;
when a concrete path is produced having a roof-shaped profile, in other words, with a surface sloping from the middle towards both lateral edges, data related to the shape of the pre-determined roof-shaped profile;
the forward speed of the paving machine;
the covered distance;
the oscillation speed of applied vibration means for vibrating the concrete;
the thickness of the concrete path, possibly calculated from other data, whether put-in or not;
when the paving machine is provided with a dowel apparatus, the adjustment of the distance where dowels and/or joints are provided;
the visualization of alarm functions;
an indication as the dowel apparatus approaches the end of its travel course.
By means of this computer system, the operator, in a centralized manner, has different data available, as a result of which an efficient validation of the operation of the paving machine and/or of the obtained result is possible.
It is clear that at random a combination can be made of the first and/or the second and/or the third and/or the fourth aspects of the invention.
Further, the invention, as mentioned in the aforegoing, also relates to a method for forming a concrete path, with as a characteristic that for forming it, a paving machine is used showing one or more of the characteristics described heretofore, whereby during forming the concrete path, a regulation of the mutual position of said parts of at least one processing device is provided for, and/or a treatment of the concrete surface is performed by means of a finishing beam which simultaneously performs an oscillating movement in upward and sideward directions, and/or a registration, as aforementioned, takes place, and/or a visualization of data by means of a computer system takes place.